The Effects of Intravenous Phosphate Loading on Salivary Phosphorus Secretion, Net Intestinal Phosphorus Absorption and Pathway of Excretion in Sheep Fed Roughage Diets

Self Cite

SUMMARYMature sheep fitted with ruminal and duodenal cannulas were fed either a pelleted hay or a pelleted grass diet with or without supplementary phosphorus. Salivary phosphorus secretion, net intestinal phosphorus absorption and the route of phosphorus excretion were determined. The route of excretion was markedly affected by diet with urinary excretion being much higher and faecal excretion lower when the grass diet was fed. These effects were not due to differences in phosphorus intake or to differences in net intestinal phosphorus absorption. Salivary phosphorus secretion was, however, lower when the grass diet was fed. The significance of these changes in relation to the control of phosphorus balance in ruminants is discussed.

Section: Discussionsupporting

confidence: 92%

“…This result provides confirmation of earlier studies in which a similar dietary effect was observed (Scott & McClean, 1981;Scott et al 1984b). …”

Section: Discussionsupporting

confidence: 82%

The Effects of Feeding Either Hay or Grass Diets on Salivary Phosphorus Secretion, Net Intestinal Phosphorus Absorption and on the Partition of Phosphorus Excretion Between Urine and Faeces in the Sheep

Scott¹,

Buchan²

1987

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“…This indicates that intestinal phosphate absorption is similar in ruminating lambs, in which large amounts of phosphate enter the digestive tract via the large volume of secreted saliva (Watson, 1933;Smith, Kleiber, Black & Baxter, 1955;Kay, 1960;Tomas, Moir & Somers, 1967;Compton, Nelson, Wright & Young, 1980;Mafias-Almendros, Ross, R. & Care, 1982;Scott, McLean & Buchan, 1984b) and in milk-fed lambs, where probably much less phosphate is secreted by the salivary glands. Unfortunately data on phosphate secretion by the salivary glands are not available for milk-fed lambs, but it has been shown that much less phosphorus enters the digestive tract via the saliva in milk-fed calves compared to cattle (Smith, Kleiber, Black & Lofgreen, 1956;Boehncke, Langner & Weissmann, 1981;Gropp, Kdnig, Feuchter & Muller, 1982).…”

Section: Discussionmentioning

confidence: 90%

Phosphate Absorption at Different Intestinal Sites in the Developing Lamb

Scharrer

1985

SUMMARYNet phosphate absorption was studied at different sites of the intestine in milk-fed lambs of different age (1 week, 3-4 weeks, 10-13 weeks) and also in lambs fed a solid diet (age: 10-13 weeks). Disappearance of phosphate from ligated intestinal segments filled or perfused with an electrolyte solution containing 1.2 mmol/l phosphate was employed as measure for phosphate absorption. In all groups of animals the mid-jejunum absorbed phosphate with the greatest velocity. In the 1-week-old lambs the proximal colon descendens was almost as efficient, though phosphate absorption at this site was minimal in the other groups of animals. With the exception of the distal jejunum, phosphate absorption appeared to decrease with age. Between animals of the same age fed either a liquid milk diet or a solid diet phosphate absorption did not differ significantly. Phosphate absorption from the mid-jejunum was inhibited by galactose and glucose in the 1-week-old lambs. The significance of these findings in relation to control of phosphate absorption in the developing lamb is discussed.

“…Further evidence for such a model comes from earlier studies (Scott, McLean & Buchan, 1984b) in which sheep given an intravascular phosphate load were seen to excrete a much higher proportion of this load in the urine when fed a grass diet compared to when fed a hay diet. Here again there was evidence that this difference in renal response was linked to reduced salivary secretion in sheep fed the more digestible grass diet.…”

Section: Discussionmentioning

confidence: 99%

The Effects of Feeding Either Roughage or Concentrate Diets on Salivary Phosphorus Secretion, Net Intestinal Phosphorus Absorption and Urinary Phosphorus Excretion in the Sheep

Scott¹,

Buchan²

1985

Self Cite

SUMMARYMature sheep fitted with rumen and duodenal cannulae were fed either a hay or a concentrate diet and the effects on salivary phosphorus secretion, net intestinal phosphorous absorption and pathway for phosphorous excretion were examined. Route of excretion was markedly affected by diet with urine phosphorus levels being much higher and faecal levels lower when the concentrate diet was fed. This difference was not due to differences in phosphorus intake nor could it be related to differences in either plasma phosphorus levels or net intestinal phosphorus absorption. Salivary phosphorus secretion and renal tubular reabsorptive efficiency for phosphorus were, however, both lower when the concentrate diet was fed. The significance of these effects ofdiet in relation to the control ofphosphorus balance in ruminants is discussed.